The proposed research forms a natural extension of the research program that I have been involved in over the past seven years. The research falls into two areas: basic research in motor control and the clinical application thereof. My immediate and long term career goals are to develop theories of motor control and use them to understand disorders of movement. In turn, the study of disordered movement will provide insight into the role of specific brain structures in the control and regulation of ordered movement. The RCDA would allow me to meet these goals in several ways. First, it will free me from a substantial departmental teaching responsibility. Second, it will free me from substantial service commitments such as serving on department, college and university committees and so forth. Third, it will provide me with the freedom to visit other research laboratories to develop new knowledge and analytic techniques. Specifically, I intend to work with Drs. P. Strick and D. Hoffman in an attempt to apply the findings of the dual-strategy hypothesis to the wrist joint. I plan to collaborate with Dr. C. D. Marsden in a series of studies extending our findings to the thumb and ascertaining the degree to which the motor deficits observed in Parkinson's disease can be observed to the same degree at proximal and distal joints. Finally, the RCDA would allow me the opportunity to learn from Dr. C. Goetz how to clinically evaluate patients with disorders of movement. Apart from freeing me from all my institutional responsibilities except teaching one course (at my request), the institution will provide me with a strongly supportive environment within which to pursue these studies. The research project has three primary aims. The first is to relate a theory of motor control (the dual-strategy hypothesis) to Parkinson's disease, Huntington's disease and cerebellar motor, deficits. The second is to study motor control at different joints to test the generality of the dual-strategy hypothesis across a wide variety of effectors. The third is to determine the degree to which movement impairment as determined by parametric measures related to the dual-strategy hypothesis correlates with disease severity as determined by the Unified Parkinson's Disease Rating Scale.